Silverlight RIA EF6代码优先SQL脚本生成未知的Discriminator字段

Question

This scenario is taking place in a complex Silverlight RIA LOB application We are upgrading the application from

EntityFramework 4 ==> EntityFramework 6
Silverlight RIA ==> Open RIA
Silverlight 4 ==> Silverlight 5
EF Database First ==> EF Code First

We have a Code First EF6 Context class like following

public DbContext()
     : base("DefaultConnection")
{
   ...
   public DbSet<Parameter> Parameters{ get; set; }
   public DbSet<ParameterType> ParameterTypes { get; set; }
}


[Table("Parameters")]
public  partial class Parameter
{
    [Key]
    public int ParameterId {get;set;}

    [InverseProperty("ParameterType")]
    public int ParameterTypeId {get;set;}

    [ForeignKey("ParameterTypeId")]
    public virtual ParameterType ParameterType { get; set; }

    public int? StoreId {get;set;}

      ...

}

[Table("ParameterTypes")]
public partial class ParameterType 
{
    [Key]
    public global::System.Int32 ParameterTypeId {get;set;}

    public global::System.String ParameterName {get;set;}

    ...

}

Everything compiles and runs well till it hits a statement

var t = Context.Parameters.ToList();

the exception states

"Invalid column name 'Discriminator'."

None of the Table fields has name "Discriminator" When I looked at the generated SQL Query it shows

{SELECT 
 CASE WHEN ([Extent1].[Discriminator] = N'Parameter') THEN '0X' WHEN     ([Extent1].[Discriminator] = N'ImportParameters') THEN '0X0X' WHEN ([Extent1].[Discriminator] = N'RecalcParameters') THEN '0X0X0X' WHEN ([Extent1].[Discriminator] = N'RolloverParameters') THEN '0X0X1X' WHEN ([Extent1].[Discriminator] = N'MassChangeParameters') THEN '0X1X' ELSE '0X2X' END AS [C1], 
    [Extent1].[ParameterId] AS [ParameterId], 
    [Extent1].[ParameterTypeId] AS [ParameterTypeId], 
    [Extent1].[StoreId] AS [StoreId], 
    [Extent1].[FiscalYear] AS [FiscalYear], 
    [Extent1].[ParameterEffectiveDate] AS [ParameterEffectiveDate], 
    [Extent1].[ParameterValue] AS [ParameterValue], 
    [Extent1].[UpdatedOn] AS [UpdatedOn], 
    [Extent1].[UpdatedBy] AS [UpdatedBy], 
CASE WHEN ([Extent1].[Discriminator] = N'Parameter') THEN CAST(NULL AS varchar(1)) WHEN ([Extent1].[Discriminator] = N'ImportParameters') THEN [Extent1].[Prompt] WHEN ([Extent1].[Discriminator] = N'RecalcParameters') THEN [Extent1].[Prompt] WHEN ([Extent1].[Discriminator] = N'RolloverParameters') THEN [Extent1].[Prompt] WHEN ([Extent1].[Discriminator] = N'MassChangeParameters') THEN CAST(NULL AS varchar(1)) END AS [C2], 

    ...

I have no idea where the Discriminator is coming from , but on the other hand why it checks it against strings like N'RecalcParameters' N'RolloverParameters' and so on.

Upon further investigation I realized that my Parameter class has another partial declaration like

[KnownType(typeof(ImportParameters))]
[KnownType(typeof(RolloverParameters))]
[KnownType(typeof(RecalcParameters))]
[KnownType(typeof(MassChangeParameters))]
[KnownType(typeof(ReforecastParameters))]
public partial class Parameter
{
    ...
}

It helps to resolve complex entities inheritance on the Silverlight client side. My Wild guess is that somehow "KnownType" attribute affects the SQL Server script generator in some way. I searched all over the internet and wasn't able to find any clue that could help me resolving this issue.

Answer 1

Use This:

    public class DbContext: DbContext
{
   public DbContext()
   {
      Configuration.ProxyCreationEnabled = false;
   }
}